An aqueous ink composition generally contains water as a main component, to which a coloring component and a wetting agent such as glycerin are incorporated. Moreover, recording media to be used for the aqueous ink composition include those capable of absorbing the ink composition to some extent and of being penetrated by a colorant, for example, paper. As a recording process using an aqueous ink composition, an ink jet recording process has recently attracted an attention. Ink jet recording process is a recording process in which droplets of an ink composition are ejected through fine nozzles and deposited onto a recording medium to conduct recording.
Hitherto, a water-soluble dye has been frequently employed as a colorant for an aqueous ink composition to be used in an ink jet printing method, so that there exists a defect that the light-fastness and water-fastness of a recorded image are poor. On the other hand, it has been examined to employ a pigment as a colorant for improving the light-fastness and water-fastness of a recorded image, but there arises a problem that fixing ability onto a recording medium is insufficient in the case of employing a pigment as a colorant.
In addition, the present inventors found the following problems. Color-bleeding may occur because the penetration rate of an ink composition is slow depending on recording media. Therefore, it has been examined to incorporate an acetylene glycol-type or glycol other-type penetrating agent. However, even in the case of an ink composition wherein the penetrating ability of the ink is enhanced by the use of the above-described penetrating agent, the penetrating ability is still insufficient depending on recording media, and thus there sometimes occurs a phenomenon that color density becomes uneven (hereinafter, referred to as “cohesion differential”). Accordingly, there is a problem that ejecting amount of the ink composition cannot be increased and thus coloring property cannot be improved, especially in the case that recording is conducted by overlapping two or more colors.
Furthermore, in the case of conventional ink compositions, the inventors have found problems of occurrence of a phenomenon that difference in reflectance is observed depending on print duties (hereinafter, referred to as “gloss differential”) and occurrence of a phenomenon that a solid print of cyan looks reddish (hereinafter, referred to as “bronzing”). In addition, it is sometimes difficult to realize image recording of a sufficiently high gloss.